Abstract:A bacterial strain with a high ability of inhibiting alternaria rot disease on pear was isolated from the pear fruits and orchard soil collected from different area across China with in vitro and in vivo methods. By morphological observation, physiological and biochemical characterization and the analysis of the 16S rDNA sequence, this strain was identified as Bacillus subtilis J18. Pretreatment with 108 CFU/mL cell suspension of B. subtilis J18 for 30s could decrease the incidence of alternaria rot on pear to 16.6% after inoculation with pathogenic fungi Alternaria alternate (Fr.) Keissler. Supplement with salicylic acid, CaCl2 and chitosan resulted in a significant increase in biocontrol effect of B. subtilis J18. It also showed that the biocontrol effect of B. subtilis J18 on pear alternaria rot could reach up to 72.81% and 77.07% when combined with 2% CaCl2 and 1% chitosan, respectively. These results revealed a potential application B. subtilis J18 as an antagonist for controlling the fruit postharvest diseases.
